Ramming in of pipes, refereed to hereafter as driven pipes, generally requires a starting trench or shaft in which the rammer and driven pipe are prepared. To reduce the dimensions of the starting trench, it is known from German Utility Model Specification 87 07 158 instead of engaging the impact tip of the rammer with the rear end of the pipe, either directly or by means of a rammer extension, to arrange it in the driven pipe. In this manner the length of the starting trench required is essentially determined merely by the length of the driven pipe.
So that the driven pipe can be rammed in, the known internal rammer is surrounded by a tubular jacket arranged in the driven pipe, with the conical impact tip of the rammer being shaped to engage and fit in an inner ring arranged at the front end of the tubular jacket (viewed in the direction of advance), so that the driving force of the rammer is transferred through the impact tip, which is either moveable or rigidly connected to the inner ring, and thus to the tubular jacket. To reverse the driving force transferred to the tubular jacket and convert it into force for driving the driven pipe forward, an outer collar is provided at the rear end of the tubular jacket (viewed in the direction of advance); which is in contact with the rear end face of the driven pipe. The driving force is thus transferred to the driven pipe via the inner ring, the tubular jacket and the outer collar. In order to avoid rebounds, which occur through the anvil effect of the outer collar of the tubular jacket lying flush on the driven pipe, the rammer and the pipe are clamped together.